1. Technical Field
The present invention relates to a novel proton type β zeolite and a preparation method thereof, and a process for preparing a phenol compound by oxidating a benzene compound such as a phenol compound or phenyl ether, etc. by a peroxide in the presence of the above zeolite and a ketone or a carboxylic acid.
2. Prior art
In a hydroxyphenyl ether represented by the following formula (a) obtained by the process for preparing a phenol compound of the present invention, for example, o-methoxy-phenol (guaiacol) in which R1 is a methyl group has been used as a starting material for medicine or perfume (13901 Chemicals, published by The Chemical Daily Co., Ltd., Japan, 2001, p. 653), and p-methoxyphenol is an important compound used as an antioxidant or a starting material for a medicine, etc. (Japanese Unexamined Patent Publication No. Hei. 9-151151).
                wherein R′ represents an alkyl group having 1 to 5 carbon atoms.        
As a technique to produce a dihydric phenol compound by oxidizing a phenol compound using zeolite as a catalyst, for example, there is an example in which faujasite or mordenite containing a rare earth metal is used is disclosed in U.S. Pat. No. 3,580,956, and an example in which in proton type ZSM-5 is used is disclosed in U.S. Pat. No. 4,578,521. Also, in French Unexamined Patent Publication No. 2,693,457, natural zeolite such as chabazite, etc., or synthetic zeolite such as US-Y, ZSM-5, etc. have been reported. However, in these techniques, yield of the objective product were not sufficient. Also, there is no description about a relationship between the strength of an acid site existing on these zeolites and a catalyst activity in the production of a dihydric phenol.
In “Advances in Catalysis”, vol. 41 (1996), pp. 253-334, an example using TS-1 (titanium is contained in the lattice of ZSM-5) has been described. However, as shown in Accounts of Chemical Research, 31 (8), (1998) pp. 485-493, TS-1 involves problems in preparation reproducibility frequently, and also yield of the objective product is not sufficient.
Also, in the “Journal of Catalysis”, vol. 203, (2001) pp. 201-212, a comparison of β zeolite containing TS-1 or titanium in the lattice is described, but for the β zeolite containing TS-1, the yield thereof based on an amount of hydrogen peroxide as a standard is 71.5%, and in the β zeolite containing titanium, it is 62.8%, so that their yields are not sufficient.
In U.S. Pat. No. 6,441,250 and Japanese Unexamined Patent Publication No. 2003-26623, there is described an example that uses β zeolite, and further disclosed that β zeolite into which an alkali metal ion has been introduced is used, yield of a dihydric phenol compound is improved. However, in the β zeolite disclosed in these references, temperature dependency with regard to a reaction yield is high, and yield at a lower temperature side of 90° C. or lower is insufficient. Accordingly, a temperature range is limited when the reaction is practically carried out, so that a further improvement has been desired.
On the other hand, in the reaction of producing a hydroxyphenyl ether with one step by oxidizing a phenyl ether, o-hydroxyphenyl ether in which the ortho-position has been oxidized and p-hydroxyphenyl ether in which the para-position has been oxidized are generally produced simultaneously (see, for example, Journal of American Chemical Society, vol. 103 (1981), pp. 3045-3049, Journal of Chemical Society Perkin Transition, vol. 1, No. 6 (1990), pp. 863-867, Journal of Chemical Society, Chemical Communications, vol. 3 (1995), pp. 349-350). Utilizability in industry of hydroxyphenyl ether may differ depending on its manner of substitution, in particular, it is markedly different from each other in an ortho-position substituted material and a para-position substituted material. For example, o-methoxyphenol is important as a starting material for medicine or perfume, and p-methoxyphenol is important as an antioxidant (see Japanese Unexamined Patent Publication No. Hei. 9-151151 and “13901 Chemicals”, published by The Chemical Daily Co., Ltd., Japan, 2001, p. 653).
Accordingly, when these materials are produced in combination, there are problems not only in yield thereof but also a formed ratio of the ortho-position substituted material and the para-position substituted material. Thus, the respective techniques to predominantly produce the ortho-position substituted material or the para-position substituted material are each important.
As a technique to predominantly produce the ortho-position substituted material or the para-position substituted material by oxidizing a phenyl ether to produce a hydroxyphenyl ether with one step, the following may be mentioned.
Of these, as a technique to use a homogeneous catalyst, in “13901 Chemicals”, published by The Chemical Daily Co., Ltd., Japan, 2001, p. 653, there is described a method for producing methoxyphenol that oxidizes anisole by hydrogen peroxide in the presence of manganese polynitroporphyline as a catalyst. In this method, yield of the methoxyphenol based on the hydrogen peroxide is as high as 98%, and whereas it shows a high para-position selectivity (a formation ratio of the ortho-position substituted material/the para-position substituted material (hereinafter referred to as an o/p ratio) of 0.11, it is difficult to obtain the catalyst with a large amount, as well as there are problems that recovery and reuse of the catalyst are difficult, so that it involves a problem when an industrial production is considered.
In Organic Preparations and Procedures Int., vol. 32 (2000), pp. 373-405, there is disclosed a preparation method of methoxyphenol from anisole using hydrogen peroxide as an oxidizing agent and copper nitrate as a catalyst. In this method, the reaction is carried out by controlling a pH of the reaction system with a phosphate buffer, whereby a high yield of 94% is accomplished as yield of the methoxyphenol based on anisole, and a high para position selectivity is obtained as an o/p ratio=0.12. However, this is a homogeneous system reaction so that recovery of the catalyst is difficult and an extremely large amount of a solvent is required, so that the procedure such as recovery thereof is complicated and trouble-some when an industrial production thereof is considered.
As a technique using a heterogeneous catalyst, in Journal of Chemical Society Chemical Communications, vol. 3 (1995), pp. 349-350, a process for preparing methoxyphenol which comprises oxidizing anisole with hydrogen peroxide by using TS-1 containing titanium in the lattice has been described. In this method, yield of the methoxyphenol based on the anisole is 67%, and an o/p ratio=0.35. As shown in the above-mentioned literature, TS-1 involves a problem in its preparation reproducibility in many times and a reaction yield is not sufficient.
In Japanese Unexamined Patent Publication No. Hei. 3-128336, a process for preparing methoxyphenol by oxidizing anisole using a catalyst system in which an alkali metal salt of a protonic acid such as sulfuric acid, etc. and an oxy acid of phosphor such as ortho phosphoric acid, etc. has been described, but there is no description about zeolite.
In French Patent Laid-Open Publication No. 2,693,457, a process for preparing methoxyphenol by oxidizing anisole by using US-Y zeolite as a proton type zeolite in the presence of a ketone has been described, but there is no description about a proton type β zeolite, and its catalyst characteristics are unknown. Also, as a result of a trace test thereof by the inventors, yield of the methoxyphenol was 47.1% (o/p ratio=2.86) so that it was insufficient (see Comparative example 7).
On the other hand, for example, in Journal of American Chemical Society, vol. 103 (1981), pp. 3045-3049, a process for preparing methoxyphenol from anisole by photooxidation using a peroxide of an azo type compound as an oxidizing agent has been described. In this process, an ortho-position substituted material is predominantly formed (a formation ratio of the ortho-position substituted material/the para-position substituted material (hereinafter referred to an o/p ratio)=1.78), but yield of the objective compound based on the oxidizing agent is 30% or so. Also, in Journal of Chemical Society Perkin Transition, 1, vol. 6 (1990), p. 863-867, a process for preparing methoxyphenol from anisole by photooxidation using an N-oxide compound having a heterocyclic structure as an oxidizing agent has been described. In this process, an ortho-position substituted material is predominantly formed (o/p ratio=1.47), but yield of the methoxyphenol based on the oxidizing agent is 42% or so in the whole yield. In these techniques, there is a merit that the reaction proceeds without any catalyst, but there is a problem that yield of the objective product is insufficient while an expensive oxidizing agent is used.
As described above, with regard to the technique to oxidize an ortho-position substituted material predominantly, there are reports in which yield of the hydroxyphenyl ether based on the oxidizing agent is 40% or so, and a technique which gives a hydroxyphenyl ether with a high yield has not yet been found out.